JP7295251B2 - PATTERN FORMATION METHOD, ELECTRONIC DEVICE MANUFACTURING METHOD - Google Patents

Description

The present invention relates to a pattern forming method and an electronic device manufacturing method. Specifically, it is suitably used for ultra-microlithography processes such as ultra-large-scale integrated circuits (LSIs) and manufacturing of high-capacity microchips, imprint mold structure manufacturing processes, and other photofabrication processes. It relates to a pattern formation method to obtain.

Conventionally, in the manufacturing process of semiconductor devices such as ICs (Integrated Circuits) and LSIs, microfabrication is performed by lithography using a photoresist composition. Recently, along with the high integration of integrated circuits, the formation of ultra-fine patterns in the nanometer range has been required. Along with this, there is a tendency for the exposure wavelength to become shorter, such as from KrF light to ArF light, and at present, lithography using electron beams and EUV (Extreme Ultraviolet) light is also being developed. Furthermore, microfabrication by lithography is not limited to the manufacture of semiconductor devices, and its application to the manufacture of mold structures (stampers) in the so-called nanoimprint technology is being studied.
Lithography using these electron beams and EUV light is positioned as a next-generation pattern forming technology, and a resist pattern forming method with high sensitivity and high resolution is desired.

The photoresist composition contains a polymer having a group that decomposes under the action of an acid to generate a polar group, and a compound that generates an acid upon exposure to actinic rays or radiation (so-called photoacid generator), which is chemically amplified. Mold resists are widely used. In addition to this, for example, a chemically amplified negative that contains a crosslinkable polymer, a crosslinker, and a photoacid generator, and that the reaction between the polymer and the crosslinker progresses under the action of an acid to form a crosslinked structure. There are also type resists, main chain scission type resists containing polymers whose main chain bonds are cut by exposure to reduce the molecular weight, and negative resists containing condensable low molecular weight compounds and in which the low molecular weight compounds are condensed by exposure. used.

Among them, as a main chain scission type resist that can easily obtain high resolution, for example, a resist whose main component is a copolymer of an α-chloroacrylate compound and an α-methylstyrene compound (for example, Nippon Zeon Co., Ltd. ZEP520A) manufactured by Co., Ltd. is also used.
The main chain scission type resist has the property that the polymer main chain is cut by exposure to electron beams, EUV light, or the like, and only the exposed portions become low-molecular-weight. Therefore, when this resist is used, a pattern is formed due to the difference in dissolution rate in the solvent between the exposed and unexposed areas.

As a developer for the main chain scission type resist as described above, for example, n-amyl acetate, which is a carboxylic acid ester solvent having an alkyl group (for example, ZED-N50 manufactured by Nippon Zeon Co., Ltd.) is widely used. . In addition, propylene glycol monomethyl ether acetate (PGMEA) (Patent Document 1), which is a carboxylic acid ester solvent having an alkoxy group, and a solvent having at least two chemical structures selected from an acetic acid group, a ketone group, an ether group, and a phenyl group (Patent Document 2) is known.
Also known is a pattern forming method using a developer containing, as a main component, a carboxylic acid compound having a total carbon number of 8 or more, which is a carboxylic acid ester having a branched alkyl group (Patent Document 3). .

Japanese Patent No. 3779882 JP 2006-227174 A Japanese Patent No. 5952613

The inventors of the present invention have studied developer solutions for main chain scission type resists with reference to Patent Documents 1 to 3, and have found that there is room for further improvement in the resolution of patterns to be formed.

Accordingly, an object of the present invention is to provide a pattern forming method capable of forming a pattern with excellent resolution using a main chain scission type resist.
Another object of the present invention is to provide a method for manufacturing an electronic device.

As a result of intensive studies aimed at solving the above problems, the inventors of the present invention have found that the above problems can be solved by the following configuration.

[1] A step of forming a resist film on a support using a resist composition containing a polymer whose main chain bond is cut by exposure to reduce its molecular weight;
exposing the resist film;
and developing the exposed resist film using a developer, wherein
The pattern forming method, wherein the developer contains an alcohol-based solvent containing a branched hydrocarbon group as a main component.
[2] The pattern forming method according to [1], wherein the alcohol-based solvent has a CLogP of 1.000 to 2.200.
[3] The pattern forming method according to [1] or [2], wherein the alcohol-based solvent has a total carbon number of 5 to 7.
[4] The pattern forming method according to any one of [1] to [3], wherein the alcoholic solvent contains one oxygen atom.
[5] the alcohol solvent is 3-methyl-2-butanol, 2-methyl-2-butanol, 2,2-dimethyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol; , 4-methyl-2-pentanol, 3,3-dimethyl-2-butanol, 2,3-dimethyl-2-butanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3- Methyl-2-pentanol, 3-methyl-3-pentanol, 3,3-dimethyl-1-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 3-methyl-1-pen Tanol, 4-methyl-1-pentanol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl-3- from the group consisting of pentanol, 4,4-dimethyl-2-pentanol, 2-methyl-2-hexanol, 2-methyl-3-hexanol, 5-methyl-2-hexanol, and 5-methyl-1-hexanol The pattern forming method according to any one of [1] to [4], wherein the solvent is one or more selected and the content of the alcohol solvent is 90% by mass or more with respect to the total mass of the developer. .
[6] The pattern forming method according to any one of [1] to [5], wherein the alcohol-based solvent is an alcohol-based solvent in which a secondary carbon or a tertiary carbon is substituted with a hydroxyl group.
[7] The pattern forming method according to any one of [1] to [6], wherein the alcohol-based solvent has 6 or 7 carbon atoms in total.
[8] The pattern forming method according to any one of [1] to [7], wherein the polymer contains an α-methylstyrene structural unit and an α-chloroacrylate structural unit.
[9] the step of developing is a step of developing using a developing device;
The pattern forming method according to any one of [1] to [8], wherein part or all of the region in the developing device that contacts the developer is made of fluorine-containing resin.
[10] The pattern forming method according to any one of [1] to [9], wherein a positive pattern is formed.
[11] A method for manufacturing an electronic device, comprising the pattern forming method according to any one of [1] to [10].

According to the present invention, it is possible to provide a pattern forming method capable of forming a pattern with excellent resolution using a main chain scission type resist.
Further, according to the present invention, it is also possible to provide a method of manufacturing an electronic device.

The present invention will be described in detail below.
The description of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
Regarding the notation of groups (atomic groups) in the present specification, as long as it does not contradict the spirit of the present invention, the notation that does not indicate substituted or unsubstituted includes groups having substituents as well as groups not having substituents. do. For example, an "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). Also, the term "organic group" as used herein refers to a group containing at least one carbon atom.
The substituent is preferably a monovalent substituent unless otherwise specified.
In the present specification, the term "~" is used to include the numerical values before and after it as lower and upper limits.
The bonding direction of the divalent groups described herein is not limited unless otherwise specified. For example, in the compound represented by the general formula "XYZ", when Y is -COO-, Y may be -CO-O- or -O-CO- may That is, the compound may be "X—CO—O—Z" or "X—O—CO—Z."
As used herein, (meth)acrylate refers to acrylate and methacrylate, and (meth)acryl refers to acrylic and methacrylic.
In this specification, "exposure" includes not only exposure using light but also drawing using particle beams such as electron beams and ion beams, unless otherwise specified. In addition, the light used for exposure generally includes the emission line spectrum of a mercury lamp, far ultraviolet rays represented by excimer lasers, extreme ultraviolet rays (EUV (Extreme Ultraviolet) light), X-rays, and actinic rays such as electron beams ( active energy rays).
In this specification, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the resin are measured by gel permeation chromatography (GPC) analysis using THF (tetrahydrofuran) as a solvent and polystyrene as a standard substance. It is the molecular weight converted using.

As used herein, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

As used herein, halogen atoms include, for example, fluorine, chlorine, bromine, and iodine atoms.

[Pattern formation method]
The pattern forming method of the present invention comprises
A step of forming a resist film on a support using a resist composition containing a polymer (hereinafter also referred to as "specific polymer") whose main chain bond is cut by exposure to reduce the molecular weight (hereinafter referred to as "resist film Also referred to as "formation process") and
A step of exposing the resist film (hereinafter also referred to as an “exposure step”);
a step of developing the exposed resist film using a developer (hereinafter also referred to as a “development step”), wherein
The developer contains an alcohol-based solvent containing a branched hydrocarbon group (hereinafter also referred to as "specific alcohol-based solvent") as a main component.

The pattern formed by the pattern forming method of the present invention having the above structure has excellent resolution. This is not clear in detail, but when the main component of the developer is a specific alcohol-based solvent, the penetration of the developer into the unexposed areas of the exposed resist film is suppressed, resulting in softening of the unexposed areas. It is presumed that pattern collapse (including pattern collapse) caused by this can be suppressed. As a result, it is believed that the formed pattern has excellent resolution.
Each procedure of the pattern forming method of the present invention will be described below.
In addition, according to the pattern forming method of the present invention, a pattern in which the exposed portion is removed by the development step, that is, a positive pattern can be formed.

[Resist film forming step (step 1)]
First, the resist composition and support that can be used in step 1 will be described below.

<Resist composition>
The resist composition contains a polymer (specific polymer) whose main chain bond is cut by exposure to reduce the molecular weight.

(specific polymer)
The specific polymer is irradiated with ionizing radiation such as electron beams and short wavelength light such as ultraviolet rays (e.g., electron beams, KrF laser, ArF laser, EUV laser, etc.) to cut the bonds of the main chain and reduce the molecular weight. It is a polymer that
The specific polymer includes a structural unit derived from an α-chloroacrylate compound (hereinafter also referred to as an "α-chloroacrylate structural unit") and a structural unit derived from an α-methylstyrene compound ( Hereinafter also referred to as “α-methylstyrene structural unit”). That is, the specific polymer is preferably a copolymer containing, as structural units (repeating units), an α-chloroacrylate structural unit and a structural unit derived from an α-methylstyrene compound.
Moreover, the copolymer preferably contains a fluorine atom from the viewpoint of further improving the absorption efficiency in EVU exposure. Since fluorine atoms have the property of easily absorbing EUV light, they have the effect of increasing absorption efficiency in EVU exposure. When the copolymer contains a fluorine atom, it is preferable that the copolymer additionally contain a structural unit containing a fluorine atom. In other words, when the copolymer contains a fluorine atom, the copolymer contains an α-chloroacrylate structural unit, an α-methylstyrene structural unit, and a structural unit containing a fluorine atom. is preferred. Note that α-chloroacrylate structural units containing fluorine atoms and α-methylstyrene structural units containing fluorine atoms correspond to structural units containing fluorine atoms.

In the above copolymer, the content of α-chloroacrylate structural units (the total content when multiple types of α-chloroacrylate structural units are included) is not particularly limited. It is preferably 10 to 90 mol %, more preferably 30 to 70 mol %, relative to all structural units.
In addition, the content of α-methylstyrene-based structural units in the copolymer (the total content when multiple types of α-methylstyrene-based structural units are included) is not particularly limited, but the entire structure of the copolymer It is preferably 10 to 90 mol %, more preferably 30 to 70 mol %, relative to the unit.

The above copolymer may contain any structural unit other than the α-chloroacrylate structural unit and the α-methylstyrene structural unit.
The total content of α-chloroacrylate structural units and α-methylstyrene structural units in the copolymer is preferably 90 mol% or more, and preferably 98 mol% or more, based on the total structural units of the copolymer. is more preferred, and 100 mol % is preferred (that is, it is preferred that the copolymer is composed only of α-chloroacrylate structural units and α-methylstyrene structural units).

In addition, as long as the copolymer has an α-chloroacrylate structural unit and an α-methylstyrene structural unit, for example, a random polymer, a block polymer, an alternating polymer (ABAB . . . ), etc. Any of them may be used, but those containing 90% by mass or more (the upper limit is 100% by mass) of the alternating polymer are preferable.

Since the copolymer contains an α-chloroacrylate structural unit and an α-methylstyrene structural unit, it can ArF laser, EUV laser, etc.) cuts the main chain to reduce the molecular weight.

Various structural units constituting the copolymer will be described below.

<<α-chloroacrylate structural unit>>
The α-chloroacrylate structural unit is a structural unit derived from an α-chloroacrylate compound.
Examples of α-chloroacrylic acid ester compounds include α-chloroacrylic acid unsubstituted alkyl esters and α-chloroacrylic acid ester derivatives.
The unsubstituted alkyl group in the α-chloroacrylic acid unsubstituted alkyl ester is preferably an unsubstituted alkyl group having 1 to 10 carbon atoms, more preferably a methyl group or an ethyl group (for example, α-chloroacrylic acid unsubstituted When the unsubstituted alkyl group in the substituted alkyl ester is a methyl group, methyl α-chloroacrylate is intended).
Examples of α-chloroacrylic acid ester derivatives include α-chloroacrylic acid halogen-substituted alkyl esters, and specific examples include α-chloroacrylic acid 2,2,2-trichloroethyl ester and α-chloroacrylic acid. 2,2,3,3,3-pentachloropropyl ester, α-chloroacrylic acid pentachlorophenyl ester, and the like.
As the α-chloroacrylic acid ester compound, among others, α-chloroacrylic acid unsubstituted alkyl ester is preferable, and α-methyl chloroacrylate or ethyl α-chloroacrylate is more preferable.

<<α-methylstyrene compound>>
The α-methylstyrene-based structural unit is a structural unit derived from an α-methylstyrene-based compound. α-Methylstyrene compounds include α-methylstyrene and derivatives thereof.
Examples of α-methylstyrene derivatives include 4-chloro-α-methylstyrene and 3,4-dichloro-α-methylstyrene.

α-Methylstyrene is preferable as the α-methylstyrene compound.

<<Structural unit containing a fluorine atom>>
The above copolymer may further contain a structural unit containing a fluorine atom in addition to the above-mentioned α-chloroacrylate structural unit and α-methylstyrene structural unit.
Examples of the structural unit containing a fluorine atom include a structural unit in which a fluorine atom is introduced into a part of the above-described α-chloroacrylate-based structural unit (hereinafter also referred to as “structural unit F-1”), and the above-described structural unit. A structural unit in which a fluorine atom is introduced into a part of the α-methylstyrene structural unit (hereinafter also referred to as "structural unit F-2"), and a structural unit having a fluorine atom other than the above structural unit (hereinafter Also referred to as “structural unit F-3”).

・ Structural unit F-1
As the structural unit (structural unit F-1) in which a fluorine atom is introduced into a part of the α-chloroacrylate structural unit, a structural unit derived from a fluorine-substituted alkyl ester compound of α-chloroacrylate is preferable. Specific examples thereof include structural units derived from the following α-chloroacrylic acid perfluoroalkyl ester compounds.

・ Structural unit F-2
As the structural unit (structural unit F-2) in which a fluorine atom is introduced into a part of the α-methylstyrene structural unit, for example, the structural unit derived from the following α-methylstyrene compound containing a fluorine atom is mentioned.

・Structural unit F-3
As the structural unit (structural unit F-3) having a fluorine atom other than the above structural units, a structural unit derived from an α-fluoroacrylic acid alkyl ester-based compound is preferable, and an α-fluoroacrylic acid fluorine-substituted alkyl ester-based Structural units derived from compounds are more preferred. Specific examples of the structural unit F-3 include structural units derived from the following α-fluoroacrylic acid perfluoroester compounds.

≪Other structural units≫
In addition to the structural units described above, the copolymer may have various structural units for the purpose of adjusting substrate adhesion, resist profile, heat resistance, sensitivity, and the like.
Examples of monomers derived from other structural units include (meth)acrylic acid, (meth)acrylate, (meth)acrylate containing a lactone structure, vinylnaphthalene, vinylanthracene, vinyl chloride, and vinyl acetate. .

The weight average molecular weight of the above copolymer is preferably 10,000 to 1,000,000, more preferably 30,000 to 120,000, even more preferably 50,000 to 70,000. When the weight-average molecular weight of the copolymer is 10,000 or more, the solubility in the developer is not too high, and as a result, the contrast between the exposed and unexposed areas of the pattern formed is more excellent.

The above copolymer can be synthesized according to a known method.

Although the copolymer is not particularly limited, specific examples thereof include copolymers of α-chloroacrylic acid unsubstituted alkyl ester and α-methylstyrene. The above copolymer is excellent in resolution and etching resistance.
Examples of the resist composition containing the copolymer include ZEP520A manufactured by Zeon Corporation.

(solvent)
The resist composition may further contain a solvent in order to improve coatability onto the substrate in step 1.
As the solvent, a known solvent can be used as long as it can dissolve the specific polymer described above. Usable solvents include, for example, anisole.

(Resist composition)
The resist composition used in step 1 contains a specific polymer as a main component.
Here, "containing a specific polymer as a main component" means that the content of the specific polymer is 90% by mass or more with respect to the total solid content of the resist composition. In this specification, the "solid content" in the resist composition is intended to be the component forming the resist film, and does not include the solvent. In addition, as long as it is a component that forms a resist film, it is regarded as a solid content even if its property is liquid.
Moreover, the resist composition may contain optional components such as a surfactant in addition to the specific polymer and solvent described above.

A resist film formed from a resist composition containing the specific polymer (particularly, the above-described copolymer) as a main component corresponds to a so-called main chain scission type resist film. That is, when the resist film is exposed to light, the bond of the main chain of the specific polymer in the resist film is cut and the molecular weight changes, thereby forming a reaction system in which the solubility in the developer is improved. As a result, the difference in solubility between the exposed area and the unexposed area becomes the contrast of the pattern, and the pattern is formed. The pattern formed using the resist composition is usually a positive pattern.

<Support>
The material of the support used in step 1 is not particularly limited, and silicon, silicon oxide, quartz, and the like can be used, for example. Specific examples of the support include a silicon wafer and a quartz substrate with a metal hard mask on which a metal hard mask made of chromium or the like is laminated.

<Resist film forming process>
Step 1 is a step of forming a resist film on a support using a resist composition.
The resist composition and support are as described above.
The content of metal atoms in the resist composition is preferably reduced.

In the following, first, a specific example of the method for reducing the content of metal atoms in the resist composition will be described, and then a specific example of the method for preparing the resist composition will be described.
Methods for reducing the content of metal atoms in the resist composition include, for example, an adjustment method by filtration using a filter. The pore size of the filter is preferably less than 100 nm, more preferably 10 nm or less, and even more preferably 5 nm or less. As the filter, a filter made of polytetrafluoroethylene, polyethylene, or nylon is preferred. The filter may be composed of a composite material combining the above filter material and ion exchange media. A filter that has been pre-washed with an organic solvent may be used. In the filter filtration step, multiple types of filters may be connected in series or in parallel for use. When multiple types of filters are used, filters with different pore sizes and/or materials may be used in combination. Further, various materials may be filtered multiple times, and the process of filtering multiple times may be a circulation filtration process.

Further, as a method for reducing the content of metal atoms in the resist composition, there is a method of selecting a raw material having a low metal content as a raw material constituting various materials in the resist composition, and a method of selecting various materials in the resist composition. Examples include a method of filtering the constituent raw materials with a filter, and a method of performing distillation under conditions in which contamination is suppressed as much as possible by, for example, lining the inside of the apparatus with Teflon (registered trademark).

In addition, as a method for reducing the content of metal atoms in the resist composition, in addition to the above-described filter filtration, removal with an adsorbent may be performed, or filter filtration and an adsorbent may be used in combination. . As the adsorbent, known adsorbents can be used. For example, inorganic adsorbents such as silica gel and zeolite, and organic adsorbents such as activated carbon can be used.
In addition, in order to reduce the content of metal atoms in the resist composition, it is necessary to prevent contamination with metal impurities during the manufacturing process. Whether or not the metal impurities are sufficiently removed from the manufacturing equipment can be confirmed by measuring the content of the metal component contained in the cleaning liquid used for cleaning the manufacturing equipment.

Next, a specific example of a method for preparing a resist composition will be described.
In the production of the resist composition, for example, after dissolving various components such as the resin and surfactant described above in a solvent, it is preferable to perform filtration (circulating filtration may be performed) using a plurality of filters made of different materials. . For example, it is preferable to connect a polyethylene filter with a pore size of 50 nm, a nylon filter with a pore size of 10 nm, and a polyethylene filter with a pore size of 3 to 5 nm in order to perform filtration. Filtration is also preferably a method of performing circulation filtration twice or more. The filtering step also has the effect of reducing the content of metal atoms in the resist composition. The pressure difference between the filters is preferably as small as possible, and is generally 0.1 MPa or less, preferably 0.05 MPa or less, and more preferably 0.01 MPa or less. The pressure difference between the filter and the filling nozzle is also preferably as small as possible, generally 0.5 MPa or less, preferably 0.2 MPa or less, more preferably 0.1 MPa or less.
As a method of performing circulation filtration using a filter in the production of the resist composition, for example, a method of performing circulation filtration two or more times using a polytetrafluoroethylene filter having a pore size of 50 nm is also preferable.

The interior of the resist composition manufacturing apparatus is preferably purged with an inert gas such as nitrogen. This can suppress the dissolution of an active gas such as oxygen into the resist composition.
After the resist composition is filtered through a filter, it is filled in a clean container. The resist composition filled in the container is preferably stored in a refrigerator. This suppresses deterioration of performance over time. The shorter the time from the completion of filling the container with the resist composition to the start of refrigeration storage, the better, generally within 24 hours, preferably within 16 hours, more preferably within 12 hours, More preferably within 10 hours. The storage temperature is preferably 0 to 15°C, more preferably 0 to 10°C, even more preferably 0 to 5°C.

Next, a method for forming a resist film on a support using the resist composition will be described.
A method of forming a resist film on a support using a resist composition includes a method of coating the support with the resist composition.

The resist composition can be applied onto a support such as those used in the manufacture of integrated circuit devices (eg, silicon, silicon dioxide coatings) by a suitable coating method such as spinner or coater. Spin coating using a spinner is preferable as the coating method. The rotation speed for spin coating using a spinner is preferably 1000 to 3000 rpm.
After coating the resist composition, the support may be dried to form a resist film. If necessary, various base films (inorganic film, organic film, antireflection film) may be formed under the resist film.

A drying method includes a method of drying by heating. Heating can be performed by a means provided in a normal exposure machine and/or a developing machine, and may be performed using a hot plate or the like. The heating temperature is preferably 80 to 200°C. The heating time is preferably 30 to 1000 seconds, more preferably 30 to 500 seconds, even more preferably 30 to 300 seconds.

Although the film thickness of the resist film is not particularly limited, it is preferably adjusted within a range of 15 to 100 nm, more preferably 20 to 40 nm, from the viewpoint of forming a finer pattern with higher precision.

[Exposure step (step 2)]
Examples of the exposure method include a method of irradiating the formed resist film with actinic rays or radiation through a predetermined mask.
Actinic rays or radiation include ultraviolet light, far ultraviolet light, extreme ultraviolet light, X-rays, and electron beams, preferably 250 nm or less, more preferably 220 nm or less, and particularly preferably far ultraviolet light having a wavelength of 1 to 200 nm. Light, specifically KrF excimer lasers (248 nm), ArF excimer lasers (193 nm), _F2 excimer lasers (157 nm), EUV (13 nm), X-rays, and electron beams.
The exposure is preferably performed using an ultraviolet irradiation device (an exposure device using an aligner, stepper, or excimer laser as a light source), an electron beam exposure device, and an EUV exposure device. As the exposure apparatus, among others, an electron beam exposure apparatus and an EUV exposure apparatus capable of irradiating a spot type beam or a variable shaped beam are preferable.

After exposure, baking (heating) may be performed before development. Baking accelerates the reaction in the exposed area, resulting in better sensitivity and pattern shape.
The heating temperature is preferably 80 to 150°C, more preferably 80 to 140°C, even more preferably 80 to 130°C.
The heating time is preferably 10 to 1000 seconds, more preferably 10 to 180 seconds, even more preferably 30 to 120 seconds.
Heating can be performed by a means provided in a normal exposure machine and/or a developing machine, and may be performed using a hot plate or the like.

[Development step (step 3)]
Step 3 is a step of developing the exposed resist film using a developer to form a pattern.
First, the developer used in step 3 will be described below.

<Developer>
The developer used in step 3 contains, as a main component, an alcohol-based solvent (specific alcohol-based solvent) containing a branched hydrocarbon group.
Here, "contains a specific alcohol-based solvent as a main component" means that the content of the specific alcohol-based solvent is 80% by mass or more with respect to the total mass of the developer.
In addition, in the developer, the specific alcohol solvent may be used singly or in combination of two or more. When the developer contains a plurality of specific alcohol-based solvents, the total content may be 80% by mass or more with respect to the total mass of the developer (in other words, it may constitute the main component of the developer). .
Moreover, the developer may contain other components than the main component. Other components include, for example, surfactants.
The content of the specific alcohol-based solvent is preferably 90% by mass or more with respect to the total mass of the developer. In addition, as an upper limit of content of a specific alcohol solvent, 100 mass % or less is preferable.

The specific alcohol-based solvent will be described below.

Specific alcohol solvents include primary alcohol solvents (alcohol solvents in which hydroxyl groups are substituted on primary carbons), secondary alcohol solvents (alcohol solvents in which hydroxyl groups are substituted on secondary carbons), and tertiary alcohol solvents. Any class alcohol solvent (alcohol solvent in which a tertiary carbon is substituted with a hydroxyl group) may be used.
Secondary alcohols or tertiary alcohols are particularly preferable as the specific alcohol solvent. By using a secondary alcohol or tertiary alcohol-based solvent, the interaction due to hydrogen bonding caused by hydroxyl groups is less likely to work. As a result, interaction between the alcohol-based solvent and the pattern is suppressed, and pattern collapse is less likely to occur. That is, the pattern resolution is more excellent.

The total carbon number of the specific alcohol solvent is preferably 4-8, more preferably 5-7. When the total number of carbon atoms in the specific alcohol-based solvent is 5 or more, the boiling point does not become too low, so volatilization is difficult, and uneven development during development can be further suppressed. When the total number of carbon atoms is 7 or less, the boiling point does not become too high, so there is an advantage that the drying time after development is shorter. The total number of carbon atoms in the specific alcohol-based solvent is more preferably 6 or 7 from the viewpoint of better resolution of the formed pattern.

The branched hydrocarbon group is not particularly limited, and may be a branched saturated hydrocarbon group or a branched unsaturated hydrocarbon group. Hydrocarbon groups are preferred.
As the branched hydrocarbon group, a branched alkyl group is particularly preferable.

The number of hydroxyl groups in the specific alcohol solvent is preferably one.
Moreover, one oxygen atom is preferably contained in the specific alcohol-based solvent. That is, the specific alcohol-based solvent preferably does not contain oxygen atoms other than the oxygen atoms contained in one hydroxyl group.
When the specific alcohol-based solvent contains oxygen atoms other than the oxygen atoms contained in hydroxyl groups, between the other oxygen atoms (more specifically, ether groups or ester groups containing other oxygen atoms) and hydroxyl groups Interactions due to hydrogen bonding are more likely to occur. By limiting the number of oxygen atoms contained in the specific alcohol-based solvent to one, the interaction can be suppressed. When the above interaction is suppressed, the formed pattern is more excellent in resolution and the solubility of the low-molecular-weight polymer component generated in the exposed area is more excellent. Furthermore, the volatility during the drying process of the pattern after development is more excellent.

In addition, the specific alcohol-based solvent preferably does not contain heteroatoms other than oxygen atoms (for example, nitrogen atoms, sulfur atoms, etc.).

Specific alcohol solvents include, for example, 3-methyl-2-butanol (ClogP: 1.002, bp: 131°C), 2-methyl-2-butanol (ClogP: 1.002, bp: 102°C), 2 , 2-dimethyl-1-propanol (ClogP: 1.092, bp: 113 ° C.), 2-methyl-1-butanol (ClogP: 1.222, bp: 130 ° C.), 3-methyl-1-butanol (ClogP : 1.222, bp: 130 ° C.), 4-methyl-2-pentanol (ClogP: 1.531, bp: 132 ° C.), 3,3-dimethyl-2-butanol (ClogP: 1.401, bp: 120° C.), 2,3-dimethyl-2-butanol (ClogP: 1.401, bp: 120° C.), 2-methyl-2-pentanol (ClogP: 1.531, bp: 121° C.), 2-methyl -3-pentanol (ClogP: 1.531, bp: 128 ° C.), 3-methyl-2-pentanol (ClogP: 1.531, bp: 134 ° C.), 3-methyl-3-pentanol (ClogP: 1.531, bp: 122° C.), 3,3-dimethyl-1-butanol (ClogP: 1.621, bp: 143° C.), 2-ethyl-1-butanol (ClogP: 1.751, bp: 146° C. ), 2-methyl-1-pentanol (ClogP: 1.751, bp: 148 ° C.), 3-methyl-1-pentanol (ClogP: 1.751, bp: 151 ° C.), 4-methyl-1- Pentanol (ClogP: 1.751, bp: 163°C), 3-ethyl-3-pentanol (ClogP: 2.06, bp: 122°C), 2,4-dimethyl-3-pentanol (ClogP: 1 .93, bp: 139° C.), 2,2-dimethyl-3-pentanol (ClogP: 1.93, bp: 132° C.), 2,3-dimethyl-3-pentanol (ClogP: 1.93, bp : 140 ° C.), 4,4-dimethyl-2-pentanol (ClogP: 1.93, bp: 137 ° C.), 2-methyl-2-hexanol (ClogP: 2.06, bp: 141 ° C.), 2- Methyl-3-hexanol (ClogP: 2.06, bp: 142° C.), 5-methyl-2-hexanol (ClogP: 2.06, bp: 149° C.), 5-methyl-1-hexanol (ClogP: 2.0° C.) 28, bp: 167°C), and 3-methyl-1-pentanol (ClogP: 1.751, bp: 151°C).
"ClogP" in parentheses is a numerical value calculated by a method described later. Moreover, "bp" represents the boiling point (°C) at normal pressure.

Specific alcohol solvents include, among others, 3-methyl-2-butanol, 2-methyl-2-butanol, 2,2-dimethyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1- butanol, 4-methyl-2-pentanol, 3,3-dimethyl-2-butanol, 2,3-dimethyl-2-butanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3 -methyl-2-pentanol, 3-methyl-3-pentanol, 3,3-dimethyl-1-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 3-methyl-1- Pentanol, 4-methyl-1-pentanol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl-3 -pentanol, 4,4-dimethyl-2-pentanol, 2-methyl-2-hexanol, 2-methyl-3-hexanol, 5-methyl-2-hexanol, and 5-methyl-1-hexanol It is preferable to use at least one selected from among them.
As the specific alcohol solvent, among the above, secondary or tertiary alcohols are preferable, and specifically, 3-methyl-2-butanol, 2-methyl-2-butanol, 4-methyl-2-pentanol, 3,3-dimethyl-2-butanol, 2,3-dimethyl-2-butanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-2-pentanol, 3-methyl -3-pentanol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl-3-pentanol, 4, It is more preferably one or more selected from the group consisting of 4-dimethyl-2-pentanol, 2-methyl-2-hexanol, 2-methyl-3-hexanol, and 5-methyl-2-hexanol.

Further, the specific alcohol-based solvent preferably has a CLogP of 1.000 or more from the viewpoint of better resolution.
When the CLogP of the specific alcohol solvent is 1.000 or more, it means that the hydrophilicity is relatively low and the polarity is low. The lower the polarity of the specific alcohol solvent (CLogP is 1.000 or more), the weaker the interaction between the specific alcohol solvent and the interaction between the pattern and the specific alcohol solvent. As a result, during drying after development, capillary force is less likely to occur between patterns, and pattern collapse is less likely to occur.
Therefore, the lower limit of CLogP is preferably 1.000 or more, more preferably 1.100 or more, and even more preferably 1.200 or more.
The upper limit of CLogP of the specific alcohol solvent is preferably 2.200 or less.
Piping tubes made of highly insulating materials such as polyethylene resins, polypropylene resins, polyethylene-polypropylene resins, and fluorine-containing resins, used in developing devices when the CLogP of the specific alcohol-based solvent is 2.200 or less. When members such as , valves, and filters come into contact with the specific alcohol-based solvent, the generation of static electricity is suppressed, and the generated static electricity is less likely to stay in the specific alcohol-based solvent. As a result of being able to suppress static electricity, it is possible to prevent risks such as damage to liquid-contacting members and/or contamination of the liquid due to discharge in the piping.
Furthermore, from the viewpoint of further preventing risks such as damage to wetted parts and/or contamination of liquid due to discharge in piping, the upper limit of CLogP is more preferably 2.000 or less, and further 1.800 or less. preferable.
"CLogP" can be calculated by ChemDraw (version.16, manufactured by PerkinElmer).

The developing method is not particularly limited, and for example, a dip method, a spray method, a paddle method, and a dynamic developing method in which a developer solution is supplied onto the wafer while the wafer is rotated can be used.

<Developing device>
The developing step is preferably carried out using a developing device conforming to the above developing method.
As a developing device, in order to prevent metal contamination of the developer, the area in contact with the developer (for example, various piping tubes, valves, developer storage containers, etc.) is preferably made of resin such as polyethylene resin, polypropylene resin, polyethylene-polypropylene resin, and fluorine-containing resin. In other words, it is preferable that the members corresponding to the regions in the developing device that come into contact with the developer are made of the resin described above. Among these resins, fluorine-containing resins are preferable. Examples of fluorine-containing resins include tetrafluoroethylene resin (PTFE), tetrafluoroethylene, perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), Fluorinated ethylene-ethylene copolymer resin (ETFE), trifluoroethylene chloride-ethylene copolymer resin (ECTFE), vinylidene fluoride resin (PVDF), trifluoroethylene chloride copolymer resin (PCTFE), and fluoride Examples include vinyl resin (PVF).

<Development conditions>
The development time is preferably adjusted within a range of, for example, 5 to 200 seconds, more preferably 5 to 60 seconds.
The developing temperature is preferably adjusted within a range of, for example, 18 to 30°C, more preferably around 23°C.

[Other processes]
The pattern forming method preferably includes a step of washing with a rinse after step 3.
As the rinsing solution used in the rinsing step after the step of developing with the developer, it is preferable to use a solvent with a lower boiling point and lower solubility than the developer, from the viewpoint of achieving both defect suppression and resolution performance. . Water, organic solvents, and mixtures thereof can be used as the solvent. In addition, the rinse liquid may contain a surfactant. Specifically, isopropyl alcohol, a mixture of isopropyl alcohol and water, and an aqueous solution containing a surfactant can be used as the rinse liquid.

The method of the rinsing step is not particularly limited, and examples thereof include a spin coating method, a dip method, and a spray method.
Moreover, the pattern forming method of the present invention may include a heating step after the rinsing step. In this step, the developing solution and the rinse solution remaining between the patterns and inside the patterns due to baking are removed. In addition, this process smoothes the resist pattern, and has the effect of improving the roughness of the surface of the pattern. The heating step after the rinsing step is usually carried out at 40 to 250° C. (preferably 90 to 200° C.) for 10 seconds to 3 minutes (preferably 30 to 120 seconds).

Also, the substrate may be etched using the formed pattern as a mask. That is, the pattern formed in step 3 may be used as a mask to process the substrate (or the underlying film and the substrate) to form a pattern on the substrate.
The method of processing the substrate (or the underlying film and the substrate) is not particularly limited, but the substrate (or the underlying film and the substrate) is dry-etched using the pattern formed in step 3 as a mask to form a pattern on the substrate. A method of forming is preferred.
Dry etching may be one-step etching or multi-step etching. When the etching is a multistage etching, the etching in each stage may be the same process or a different process.
Any known method can be used for etching, and various conditions and the like are appropriately determined according to the type of the substrate, the application, and the like. For example, Proc. of SPIE Vol. 6924, 692420 (2008), Japanese Patent Application Laid-Open No. 2009-267112, etc., can be used for etching. Alternatively, the method described in "Chapter 4 Etching" of "Semiconductor Process Textbook, 4th Edition, 2007 Publisher: SEMI Japan" can also be used.

A method for improving surface roughness of the pattern may be applied to the pattern formed by the method of the present invention. As a method of improving the surface roughness of the pattern, for example, a method of treating the pattern with hydrogen-containing gas plasma disclosed in WO 2014/002808 can be mentioned. In addition, Japanese Patent Application Publication No. 2004-235468, US Patent Application Publication No. 2010/0020297, Japanese Patent Application Publication No. 2008-83384, and Proc. of SPIE Vol. 8328 83280N-1 "EUV Resist Curing Technique for LWR Reduction and Etch Selectivity Enhancement".

When the pattern to be formed is linear, the aspect ratio obtained by dividing the pattern height by the line width is preferably 2.5 or less, more preferably 2.1 or less, and even more preferably 1.7 or less. .
When the pattern to be formed is a trench (groove) pattern or a contact hole pattern, the aspect ratio obtained by dividing the pattern height by the trench width or hole diameter is preferably 4.0 or less, and preferably 3.5. The following is more preferable, and 3.0 or less is even more preferable.

The pattern forming method of the present invention can also be used for guide pattern formation in DSA (Directed Self-Assembly) (see, for example, ACS Nano Vol.4 No.8 Pages 4815-4823).

Also, the pattern formed by the above method can be used as a core for the spacer process disclosed in, for example, JP-A-3-270227 and JP-A-2013-164509.

[Method for manufacturing electronic device]
The present invention also relates to a method of manufacturing an electronic device, including the pattern forming method described above. The electronic device is suitably mounted in electrical and electronic equipment (household appliances, OA (Office Automation), media-related equipment, optical equipment, communication equipment, etc.).

The present invention will be described in more detail below based on examples. Materials, usage amounts, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the examples shown below.

[Pattern formation and evaluation]
[Resist film forming step]
First, a 6-inch silicon wafer substrate was coated with a composition for forming an organic base film (AL412, manufactured by Brewer Science) to a thickness of 20 nm to form a coating film. Next, the coating film was baked at 205° C. for 60 seconds to prepare a silicon substrate with an organic undercoat.
Next, a resist composition was prepared by diluting ZEP520A (manufactured by Nippon Zeon Co., Ltd.) with anisole. This resist composition was applied by spin coating onto the silicon substrate having the above-mentioned organic undercoat to form a coating film. By baking this coating film at 180° C. for 60 seconds, a resist film having a thickness of 30 nm was formed on the silicon wafer.

[Exposure process]
An exposure step was performed on the silicon wafer with the resist film thus produced. Specifically, using an EB exposure apparatus (ELS-G100, acceleration voltage of 100 kV, manufactured by Elionix), a plurality of line-and-space patterns (line/space = 1/1) with a half pitch (line width) of 15 to 50 nm were used. ) was drawn on the same resist film.

[Development process]
Then, the resist film after exposure was developed. Solvents 1 to 14 in Table 1 were used as developers. The development conditions are as follows.
Discharge time of developer: 10 seconds Number of rotations of wafer during discharge of developer: 500 rpm Immediately after discharging developer, start spin drying.
Spin dry rotation speed: 2000 rpm Spin dry time: 30 seconds

A pattern from which the exposed portion was removed, that is, a positive pattern was formed by the above development process.

Table 1 is shown below.
"CLogP" in the table is a numerical value calculated by ChemDraw (version.16, manufactured by PerkinElmer).
"bp" in the table represents the boiling point (°C) at normal pressure.

[Resolution performance evaluation]
A plurality of produced line-and-space patterns with a half pitch (line width) of 15 to 50 nm were observed from the top of the pattern using a scanning electron microscope (SEM (Hitachi Ltd. S-9380II)). We then evaluated the resolution. Specifically, the resolution was evaluated based on the minimum line width (nm) capable of forming a line-and-space pattern free from defects caused by pattern collapse. A smaller value indicates better performance.

[Evaluation of static electricity suppression]
Based on the evaluation criteria below, the static electricity suppressing property of the developer was evaluated.
If the CLogP value of the solvent is 2.200 or less: no problem (judgment A)
If the CLogP value of the solvent exceeds 2.200: there is concern (judgment B)

Table 2 is shown below.

From the results in Table 2, it is clear that the patterns formed by the pattern forming methods of Examples have excellent resolution.
Further, from the comparison of Examples 1 to 5, it is clear that pattern resolution is more excellent when the total number of carbon atoms in the alcohol-based solvent is 6 or 7.
Further, from the comparison of Examples 2 to 6, it is clear that pattern resolution is better when the alcohol-based solvent is a secondary alcohol or a tertiary alcohol.
On the other hand, Comparative Examples 1, 2, 5, 6, 7 and 8 using solvents 7, 8, 11, 12, 13, and 14, which are alcohol-based solvents having no hydrocarbon containing a branched chain structure, as the developer, Also, in Comparative Examples 3 and 4 in which solvents 9 and 10, which are non-alcoholic solvents, are used as developers, the resolution of the patterns formed does not meet the desired requirements.

Claims (9)

a step of forming a resist film on a support using a resist composition containing a polymer whose main chain bond is cut by irradiation with an electron beam or ultraviolet rays to reduce its molecular weight;
a step of exposing the resist film by irradiation with electron beams or ultraviolet rays ;
and developing the exposed resist film using a developer, wherein
the polymer comprises an α-methylstyrene-based structural unit and an α-chloroacrylate-based structural unit;
The developer contains an alcohol-based solvent containing a branched hydrocarbon group as a main component,
The pattern forming method , wherein the alcohol-based solvent has a CLogP of 1.000 or more and a total carbon number of 5 to 7 . 2. The pattern forming method according to claim 1, wherein CLogP of said alcoholic solvent is 1.000 to 2.200. 3. The pattern forming method according to claim 1 , wherein the alcohol solvent contains one oxygen atom. The alcohol solvent is 3-methyl-2-butanol, 2-methyl-2-butanol, 2,2-dimethyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 4- Methyl-2-pentanol, 3,3-dimethyl-2-butanol, 2,3-dimethyl-2-butanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-2 -pentanol, 3-methyl-3-pentanol, 3,3-dimethyl-1-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 4 -methyl-1-pentanol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl-3-pentanol, 1 selected from the group consisting of 4,4-dimethyl-2-pentanol, 2-methyl-2-hexanol, 2-methyl-3-hexanol, 5-methyl-2-hexanol, and 5-methyl-1-hexanol 4. The pattern forming method according to any one of claims 1 to 3 , wherein the content of the alcohol-based solvent is 90% by mass or more with respect to the total mass of the developer. The pattern forming method according to any one of claims 1 to 4 , wherein the alcohol-based solvent is an alcohol-based solvent in which a secondary carbon or a tertiary carbon is substituted with a hydroxyl group. 6. The pattern forming method according to claim 1, wherein the alcohol-based solvent has 6 or 7 carbon atoms in total. The developing step is a step of developing using a developing device,
7. The pattern forming method according to any one of claims 1 to 6 , wherein part or all of a region in said developing device that contacts said developer is made of fluorine-containing resin. The pattern forming method according to any one of claims 1 to 7 , wherein a positive pattern is formed. A method for manufacturing an electronic device, comprising the pattern forming method according to any one of claims 1 to 8 .